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Full text of "Metallurgy Of Cast Iron"

CHAPTER XV.
UTILITY   OF   DIRECT   METAL   FOR FOUNDING.
In the first days of founding, castings were made from metal taken directly from the furnace making the iron. The difficulty and uncertainty of obtaining the grade of iron desired and the fluidity necessary to insure good work, as well as the advantage of having metal at the time best suited to the founder's needs, gave rise to the origination of the cupola to re-melt iron. Had the furnace advanced anywhere near the degree in assuring a uniformity of " grade " that it has in increasing its output many more castings would now be made direct from furnace iron.  While some may question the ability of the furnace to ever achieve any better results in always obtaining a uniformity of product, competition may strongly influence an effort for improvement in this direction. Aside from the' above evil is that of the trouble caused by the " kish " found with some metals that throw out graphite' excessively. Often after a furnace '' cast'' of Foundry or Bessemer the floor of the house will be covered with " kish," which resembles in appearance flakes of silver lead or plumbago, and are like the flakes of carbon so often found between grains of pig metal and castings. It can be removed from fractures by means of a stiff brush or rubbing.e percentage of silicon and sulphur in tlie iron. Iron above 1.20 silicon and not over .04 in sulphur, with manganese below 1.25, will rarely show any chill, but, of course, be more dense or higher in combined carbon than if the same iron was cast in sand moulds. Cuts of sand and chilled cast pig are shown in Figs. 35 and 36. These cuts were originally presented by Mr. Alfred Ladd Colby in the Iron Trade Review, June 13, 1901. during 1899 by courtesy of Mr. Edgar S. Cook, president of the Warwick Iron Co. of Pottstown, Pa. is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................    2,720     "